size = int(input("请输入棋盘的大小："))

# 确保输入为正整数
if size < 1:
    print("请输入大于0的整数")
else:
    for i in range(1, size * 2):  # 行循环：实际行数是尺寸的2倍减1
        for j in range(1, size * 2):  # 列循环：实际列数是尺寸的2倍减1
            # 角落特殊字符
            if (i == 1 and j == 1):
                print("┌", end="")
            elif (i == 1 and j == size * 2 - 1):
                print("┐", end="")
            elif (i == size * 2 - 1 and j == 1):
                print("└", end="")
            elif (i == size * 2 - 1 and j == size * 2 - 1):
                print("┘", end="")
            
            # 横线与交叉点
            elif i % 2 == 1:  # 奇数行：横线
                if j % 2 == 1:  # 奇数列：交叉点
                    print("┼", end="")
                else:  # 偶数列：横线
                    print("─", end="")
            
            # 竖线
            elif i % 2 == 0:  # 偶数行：竖线
                if j % 2 == 1:  # 奇数列：竖线
                    print("│", end="")
                else:  # 偶数列：空白（网格内容区）
                    print(" ", end="")
        print()  # 换行